In supercharged engines, an intake device such as this comprises a main circuit incorporating an intercooler and connecting a supercharger such as a compressor of a turbocompressor to the intake duct of the heat engine. The supercharger further comprises a non-cooled bypass circuit connected to the main circuit on each side of the intercooler. Valves are fitted on the main circuit and the bypass circuit and are controlled by the engine electronic control unit (ECU) in order to direct air toward one or other circuit so as to obtain, in the intake duct, an air temperature that is suited to the desired engine performance.
This system is not, however, always capable of obtaining optimal engine operation, particularly at start-up and at low idle.